It is highly important to acquire blood pressure information of a subject for knowing a health condition of the subject. In recent years, there have been attempts to capture changes in a cardiac load and hardness of an artery not only by acquiring a systolic blood pressure value (a maximal blood pressure value), a diastolic blood pressure value (a minimal blood pressure value), and the like, which are conventionally widely recognized as useful representative indicators for health management, but also by acquiring a pulse wave of the subject. A blood pressure information measurement device is a device for obtaining these indicators for health management based on the acquired blood pressure information, and such a device is expected to be further utilized in fields of early detection, prevention, and treatment of circulatory diseases, and the like. It should be noted that the blood pressure information widely includes various information relating to a circulatory system such as the systolic blood pressure value, the diastolic blood pressure value, an average blood pressure value, the pulse wave, pulsation, and an AI (Augmentation Index) value.
In general, a cuff accommodating a fluid bag is utilized for measurement of the blood pressure information. The cuff is a band-shaped structure having an inner cavity that is capable of being wound around part of a living body, the cuff being utilized for the measurement of the blood pressure information by infusing a fluid such as gas and a liquid into the inner cavity so as to expand and contract the fluid bag. For example, in the blood pressure information measurement device (hereinafter, also simply referred to as a sphygmomanometer) for measuring the blood pressure values such as the systolic blood pressure value and the diastolic blood pressure value, the cuff accommodating the fluid bag for compressing the artery is wound around a body surface of the living body, and the wound fluid bag is expanded and contracted, so that an arterial blood pressure pulse wave is captured as a change in inner pressure of the fluid bag. Thus, the blood pressure values are measured. It should be noted that a cuff particularly wound around an arm and used in this way is also called an arm band or a manchette.
In the cuff, there is a need for reliably winding a cuff main body portion to be attached to a measurement site around the living body so as to reliably fix the fluid bag to the measurement site of the living body. However, in a general cuff, because a winding task is left to the hands of the subject, reliable winding is not always reproduced. In a case where the reliable winding is not reproduced, measurement values are varied, making it difficult to precisely and stably measure the blood pressure information.
Thus, variously formed cuffs have been conventionally proposed for reliably winding the cuff around the measurement site with favorable reproducibility. For example, Japanese Unexamined Patent Publication No. S61-238229 (Patent Document 1), Japanese Unexamined Patent Publication No. 2002-209858 (Patent Document 2), and the like disclose a cuff accommodating a curved elastic plate called a curler inside in addition to an air bladder serving as the fluid bag. The curler is accommodated inside the cuff for maintaining an annular form of the cuff. The curler is annularly wrapped around an outer side of the air bladder and arranged inside the cuff, so that the cuff is formed to be elastically deformable in a radial direction. In the cuff provided with such a curler, the air bladder is fixed while being pushed toward the measurement site by the curler with proper pressing force after attachment. Thus, reliable fixation of the air bladder to the measurement site is reproduced.
However, in the cuff accommodating the above curler, the curler is shaped so that the curler at the time of non-attachment has a more reduced diameter than the measurement site in order to reliably press the air bladder onto the measurement site at the time of attaching the cuff. As such, the curler in a reduced diameter state is required to be once pushed and extended before attachment to the measurement site.
In order to further easily attach the cuff accommodating the above curler, Japanese Unexamined Patent Publication No. 2006-68318 (Patent Document 3) discloses a configuration of a cuff attachable to and detachable from the measurement site with a single touch operation. In the cuff disclosed in Japanese Unexamined Patent Publication No. 2006-68318, an elastic member such as a bias spring and a power transmission mechanism such as a slider are built inside the cuff, so that the cuff is attached to the measurement site with favorable reproducibility by a bias force of the bias spring with an optimal tightening force, and the size of the cuff including the curler in the radial direction is variable in conjunction with the operation of a user. Thereby, the cuff can be attached and detached with the single touch operation.
Japanese Unexamined Patent Publication No. 2007-75294 (Patent Document 4) and International Publication WO 03/101290 (Patent Document 5) disclose a cuff in which a winding device including a bias spring and a winding roller is built inside the cuff, and one end of a band-shaped belt member to which an air bladder is attached is wound by the winding device, so that the cuff is attached to the measurement site with favorable reproducibility by a bias force of the bias spring with optimal tightening force.
Patent Document 1: Japanese Unexamined Patent Publication No. S61-238229
Patent Document 2: Japanese Unexamined Patent Publication No. 2002-209858
Patent Document 3: Japanese Unexamined Patent Publication No. 2006-68318
Patent Document 4: Japanese Unexamined Patent Publication No. 2007-75294
Patent Document 5: International Publication WO 03/101290
However, in the cuff disclosed in Japanese Unexamined Patent Publication No. 2007-75294 and International Publication WO 03/101290, the cuff in the non-attachment state has a non-annular form. Thus, there is a need for fixing the cuff to the measurement site in a state that the cuff is annularly wrapped around the measurement site, so that engagement portions for engagement are provided in one end and another end of the band-shaped belt member. In a case of the cuff with such a configuration, there is a need for engaging the engagement portions while maintaining a state that the band-shaped belt member is placed on the measurement site during attachment. Thus, because it is difficult to perform the operation with a single hand, the operation is forced to be performed with both hands. Therefore, in a case where the cuff with the above configuration is adopted in a sphygmomanometer for a domestic use which requires the subject winding the cuff around one of his/her arms by himself/herself, there is a problem that the attachment of the cuff is not easily performed by himself/herself in the first place.
Meanwhile, in the cuff disclosed in Japanese Unexamined Patent Publication No. 2006-68318, the cuff has an annular form in the non-attachment state. Thus, by inserting the measurement site into a hollow opening portion thereof, the cuff can be attached and detached with a single touch operation of a single hand. However, for convenience of the configuration of the device, the size of the cuff including the curler in the radial direction cannot be varied without restriction, so there is a problem that applicable circumferential length of the measurement site is restricted.
Therefore, one or more embodiments of the present invention provides a cuff for a blood pressure information measurement device capable of being easily attached to a measurement site of a living body in which applicable circumferential length of the measurement site is not restricted, and a blood pressure information measurement device provided with the same.